In the use of bolt and expansion shell assemblies for supporting mine roofs, it has been conventional practice to interpose a support member between the bolt head and the mine roof in order to afford greater surface area contact with the mine roof. These suport members have, in the past, taken the form of pieces of wood and more recently, plates made of steel or other strong metallic material. Examples of metallic plates are found in U.S. Pat. Nos. 3,238,73l, 3,478,523 and 4,037,418.
It will be noted from a consideration of the support plates of the above-noted patents that the design thereof requires the use of ductile alloys in order to form a support plate of this desired shape. This increases the cost of the support plate.
Also, in the installation of support plates and mine roof bolt assemblies, installation is effected by inserting the roof bolt through the central opening of the supporting plate, following which an expansion shell is threaded on the roof bolt. The bolt and expansion shell are then inserted into a mine roof opening and the bolt tightened. This necessitates holding the heavy supporting member and bolt while the expansion shell is threaded thereon, with resultant strain and fatigue on the installer when a member of the assemblies are positioned in the mine roof.